I have an ASF file created by my JVC video camera in what it calls an "MPEG-4 email clip" format. The clip plays fine in Windows Media Player 6.4

I want to convert the clip to DivX. I have installed the old Virtual Dub 1.3c which is supposed to open ASF files as well as the SMR patch for it. When I try to open the file in Virtual Dub it gives me an error and says it cannot find the required MP4S decompressor.

How can I open this file in Virtual Dub and is a suitable MP4S codec available anywhere? MP4S seems to be very similar to MPEG-4, but there is something different about it that I don't understand.